GCSE Add Applied Science June 2008 Scientific Detection Paper B

* C U P /T 4 3 7 4 3 * This document consists of 11 printed pages and 1 blank page. SPA (SJF4647/CG) T43743/5 © OCR 2008 [M/103/3781] OCR is an exempt Charity [Turn over INSTRUCTIONS TO CANDIDATES • Write your name in capital letters, your Centre Number and Candidate Number in the boxes above. • Use blue or black ink. Pencil may be used for graphs and diagrams only. • Read each question carefully and make sure that you know what you have to do before starting your answer. • Answer all the questions. • Do not write in the bar codes. • Write your answer to each question in the space provided. INFORMATION FOR CANDIDATES • The number of marks for each question is given in brackets [ ] at the end of each question or part question. • The total number of marks for this paper is 36. FOR EXAMINER’S USE Qu. Max Mark 1 8 2 6 3 3 4 6 5 13 TOTAL 36 GENERAL CERTIFICATE OF SECONDARY EDUCATION A325/02 TWENTY FIRST CENTURY SCIENCE ADDITIONAL APPLIED SCIENCE A Scientific Detection (Higher Tier) WEDNESDAY 18 JUNE 2008 Afternoon Time: 45 minutes Candidates answer on the question paper. Additional materials (enclosed): None Calculators may be used. Additional materials: Pencil Ruler (cm/mm) H2 © OCR 2008 Answer all the questions. 1 Steve is a forensic scientist. He attends the crime scene of a murder. Detectives have cordoned off the scene of crime area. (a) The area measures 10.5 metres by 8.6 metres. (i) Calculate the size of the cordoned off area in square metres. Show your working. answer ................................................... m2 [1] (ii) Explain why the calculated area has a greater uncertainty than the measured lengths. .......................................................................................................................................... .......................................................................................................................................... ......................................................................................................................................[2]3 [Turn over © OCR 2008 (b) Steve measures the diameter of the bullet found in the body. He uses a Vernier scale to measure the diameter of the bullet. 0 1 2 0 5 10 (i) Record the reading from the Vernier scale. answer ................................................... cm [2] (ii) Steve uses the following standard procedure for using the Vernier scale. The steps are in the wrong order. A Note the reading from the bottom scale. B Adjust the jaws so that they are both touching each side of the bullet. C Read the top main scale including the first decimal place. D Place the bullet in the jaws of the Vernier scale. E Look for the two graduations that line up. Fill in the boxes to show the right order. The first one has been done for you. D [3] [Total: 8]4 © OCR 2008 2 Freya works in a laboratory. She uses this standard procedure to estimate the concentration of an unknown solution by colour matching. step 1 160 ppm Prepare a reference solution of the coloured compound at a concentration of 160 parts per million (ppm). step 2 Pipette 5 cm3 of distilled water into each of three test tubes. step 3 80 ppm Pipette 5 cm3 of the reference solution into the first test tube and label it 80 ppm. step 4 Then, suck the liquid into and squeeze the liquid out of the pipette several times. step 5 40 ppm Pipette 5 cm3 of the mixture in the first test tube into the second test tube. Label the second test tube 40 ppm. Repeat step 4. step 6 20 ppm Pipette 5 cm3 of the mixture in the second test tube into the third test tube. Label the third test tube 20 ppm. Repeat step 4. step 7 160 80 40 20 unknown Compare the colour intensity of the unknown solution with the four prepared reference solutions.5 [Turn over © OCR 2008 (a) Choose from the following statements to help you answer the questions. • So there is always the same volume of liquid in each test tube. • To mix up the solution. • So the pipette does not contaminate all the other test tubes. • To get a closer match. • Because the unknown solution is unlikely to exactly match one of the reference solutions. • So it is the same every time. (i) Why did Freya produce four reference solutions, rather than just one? .......................................................................................................................................... ..................................................................................................................................... [1] (ii) Why did Freya perform step 4? .......................................................................................................................................... ..................................................................................................................................... [1] (iii) Why is this method unlikely to give Freya an exact result? .......................................................................................................................................... ..................................................................................................................................... [1] (iv) Why does Freya use a standard procedure for this activity? .......................................................................................................................................... ..................................................................................................................................... [1] (b) Freya then uses a colorimeter to check her results. (i) Suggest why Freya does this. Use one of the following words in your answer. accreditation accurate chromatography microscope .......................................................................................................................................... ..................................................................................................................................... [1] (ii) Which of the following words best describes the results obtained by using a colorimeter? Choose from the following list. Put a ring around the best answer. qualitative quantitative semi-quantitative [1] [Total: 6]6 © OCR 2008 3 Good laboratory practice is essential to produce reliable evidence. Complete the crossword. All the clues are about good laboratory practice. Some of the letters have been completed for you. 1 23 4 C C EY S L B T NY Across 1 A type of test used to check a laboratory. 3 What laboratories get when they pass the test. 4 Good laboratory practice produces ……………………… evidence. Down 1 Reliability is increased by using common practice and ……………………… . 2 Complete the following phrase. ‘Health and ………………………’ [3] [Total: 3]7 [Turn over © OCR 2008 4 Neil uses chromatography to analyse an unknown solution X. Look at the diagram of Neil’s chromatogram. X Y paper solvent front mobile phase stationary phase start line water front view from the side (a) Label the side-view of Neil’s chromatogram. Use the words next to the diagram. [3] (b) Draw an arrow on Neil’s side-view diagram to show the movement of substances between the mobile phase and the stationary phase. [1] (c) Neil uses Y as a standard reference solution. What conclusion can Neil make about X and Y? Explain your answer. .................................................................................................................................................. .................................................................................................................................................. ............................................................................................................................................. [2] [Total: 6]8 © OCR 2008 5 Suniel uses a colorimeter to measure the concentration of a coloured food dye in a soft drink. (a) The flow diagram shows the sequence of events that occurs in the colorimeter. Complete the flow diagram. Choose words from the following list. continuous phase filter light-sensitive cell meter paper strip test solution light source [3] (b) Suniel first calibrates the machine by using pure water. Give two reasons why. .................................................................................................................................................. .................................................................................................................................................. ............................................................................................................................................. [2]9 [Turn over © OCR 2008 (c) Calibration readings were taken for a series of standard reference solutions. concentration (g /dm3) absorbance 0.2 0.15 0.4 0.32 0.6 0.47 0.8 0.58 1.0 0.75 (i) Use Suniel’s data to plot a calibration graph. concentration in g /dm3 absorbance [3] (ii) Suniel’s soft drink had an absorbance of 0.24. Use the graph to work out the concentration of the food dye in the soft drink. Draw straight lines on your graph to show how you worked out your answer. concentration = ............................................. g /dm3 [2]10 © OCR 2008 (d) Draw straight lines from each description of what a colorimeter does to the correct missing word. description missing word colour Colorimeters measure the …………… of a colour. concentration intensity This can be used to find out the ………………. of a coloured chemical in solution. qualitative quantitative A colorimeter provides …………….. data about a coloured solution. frequency [3] [Total: 13] END OF QUESTION PAPER11 © OCR 2008 BLANK PAGE PLEASE DO NOT WRITE ON THIS PAGE12 © OCR 2008 PLEASE DO NOT WRITE ON THIS PAGE Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (OCR) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. OCR is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.